Various apparatus have been proposed heretofore for measuring the resistance of the lungs and other physiological characteristics of the lungs, both on an alternating pressure and on a unidirectional pressure basis. However, most of these prior proposed arrangements have been open systems, or have been directed to the analysis of a single or only a few pulmonary characteristics. Accordingly, the results obtained from such prior tests tend to be incomplete and relatively inconclusive, although many of the prior art arrangements were quite useful in obtaining preliminary insights into certain pulmonary functions and phenomena.
Accordingly, a principal object of the present invention is to provide a more complete and comprehensive technique for the analysis of pulmonary functions and effects, both under unidirectional and alternating pressure conditions, and to combine this information with a complete analysis of the volumes of air inhaled and exhaled by the subject, particularly under maximum expiratory air flow conditions.